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在数字排版中，字体定义了用于字符外观的特定样式。通常，在文档和网页中使用字体来样式化文本。每种字体都在一个文件中进行了描述，该文件包含有关字符的大小，粗细，样式和编码的信息。

对于此类情况，Aspose提供了专用的API——Aspose.Font，用于处理和渲染包括TrueType，CFF，OpenType和Type1在内的流行字体类型。

在上一篇文章中，您已经了解了如何使用Aspose.Font for .NET API来以编程方式加载和保存CFF，TrueType和Type1字体。在本文中，将学习如何使用C＃呈现TrueType和Type1字体的文本。

点击下载最新版Aspose.Font for .NET

实施文本渲染界面

为了实现文本呈现，.NET的Aspose.Font提供了IGlyphOutlinePainter接口来绘制字形。以下步骤演示了如何在IGlyphOutlinePainter中实现这些方法。

• 使用GlyphOutlinePainter类实现IGlyphOutlinePainter接口方法，该类需要一个类型为System.Drawing.Drawing2D.GraphicsPath的对象才能绘制图形。
  

  class GlyphOutlinePainter : IGlyphOutlinePainter
  {
      private System.Drawing.Drawing2D.GraphicsPath _path;
      private System.Drawing.PointF _currentPoint;
  
      public GlyphOutlinePainter(System.Drawing.Drawing2D.GraphicsPath path)
      {
          _path = path;
      }
  
      public void MoveTo(MoveTo moveTo)
      {
          _path.CloseFigure();
          _currentPoint.X = (float)moveTo.X;
          _currentPoint.Y = (float)moveTo.Y;
      }
  
      public void LineTo(LineTo lineTo)
      {
          float x = (float)lineTo.X;
          float y = (float)lineTo.Y;
          _path.AddLine(_currentPoint.X, _currentPoint.Y, x, y);
          _currentPoint.X = x;
          _currentPoint.Y = y;
      }
  
      public void CurveTo(CurveTo curveTo)
      {
          float x3 = (float)curveTo.X3;
          float y3 = (float)curveTo.Y3;
  
          _path.AddBezier(
                    _currentPoint.X,
                    _currentPoint.Y,
                    (float)curveTo.X1,
                    (float)curveTo.Y1,
                    (float)curveTo.X2,
                    (float)curveTo.Y2,
                    x3,
                    y3);
  
          _currentPoint.X = x3;
          _currentPoint.Y = y3;
      }
  
      public void ClosePath()
      {
          _path.CloseFigure();
      }
  }

• 创建一个新方法DrawText（）将文本绘制到System.Drawing.Bitmap对象中。
  

  static void DrawText(string text, IFont font, double fontSize,
              Brush backgroundBrush, Brush textBrush, string outFile)
  {
      //Get glyph identifiers for every symbol in text line
      GlyphId[] gids = new GlyphId[text.Length];
      for (int i = 0; i < text.Length; i++)
          gids[i] = font.Encoding.DecodeToGid(text[i]);
      // set common drawing settings
      double dpi = 300;
  
      double resolutionCorrection = dpi / 72; // 72 is font's internal dpi
      // prepare output bitmap
      Bitmap outBitmap = new Bitmap(960, 720);
      outBitmap.SetResolution((float)dpi, (float)dpi);
      Graphics outGraphics = Graphics.FromImage(outBitmap);
      outGraphics.FillRectangle(backgroundBrush, 0, 0, outBitmap.Width, outBitmap.Height);
      outGraphics.SmoothingMode = SmoothingMode.HighQuality;
      //declare coordinate variables and previous gid
      GlyphId previousGid = null;
      double glyphXCoordinate = 0;
      double glyphYCoordinate = fontSize * resolutionCorrection;
      //loop which paints every glyph in gids
      foreach (GlyphId gid in gids)
      {
          // if the font contains the gid
          if (gid != null)
          {
              Glyph glyph = font.GlyphAccessor.GetGlyphById(gid);
              if (glyph == null)
                  continue;
  
              // path that accepts drawing instructions
              GraphicsPath path = new GraphicsPath();
  
              // Create IGlyphOutlinePainter implementation
              GlyphOutlinePainter outlinePainter = new GlyphOutlinePainter(path);
  
              // Create the renderer
              Aspose.Font.Renderers.IGlyphRenderer renderer = new
                  Aspose.Font.Renderers.GlyphOutlineRenderer(outlinePainter);
  
              // get common glyph properties
              double kerning = 0;
  
              // get kerning value
              if (previousGid != null)
              {
                  kerning = (font.Metrics.GetKerningValue(previousGid, gid) /
                             glyph.SourceResolution) * fontSize * resolutionCorrection;
                  kerning += FontWidthToImageWith(font.Metrics.GetGlyphWidth(previousGid),
                          glyph.SourceResolution, fontSize);
              }
  
              // glyph positioning - increase glyph X coordinate according to kerning distance
              glyphXCoordinate += kerning;
  
              // Glyph placement matrix
              TransformationMatrix glyphMatrix =
                  new TransformationMatrix(
                      new double[]
                              {
                                      fontSize*resolutionCorrection,
                                      0,
                                      0,
                                  // negative because of bitmap coordinate system begins from the top
                                      - fontSize*resolutionCorrection,
                                      glyphXCoordinate,
                                      glyphYCoordinate
                              });
  
              // render current glyph
              renderer.RenderGlyph(font, gid, glyphMatrix);
              // fill the path
              path.FillMode = FillMode.Winding;
              outGraphics.FillPath(textBrush, path);
          }
          //set current gid as previous to get correct kerning for next glyph
          previousGid = gid;
      }
      //Save results
      outBitmap.Save(outFile);
  }

• 定义一种实用程序方法，以根据图像的宽度计算字体的宽度。
  

  static double FontWidthToImageWith(double width, int fontSourceResulution, double fontSize, double dpi = 300)
  {
      double resolutionCorrection = dpi / 72; // 72 is font's internal dpi
      return (width / fontSourceResulution) * fontSize * resolutionCorrection;
  }

使用C＃渲染具有TrueType字体的文本

下面的代码示例演示如何使用上述实现通过C＃使用TrueType字体呈现文本。

string dataDir = RunExamples.GetDataDir_Data();

string fileName1 = dataDir + "Montserrat-Bold.ttf"; //Font file name with full path
FontDefinition fd1 = new FontDefinition(FontType.TTF, new FontFileDefinition("ttf", new FileSystemStreamSource(fileName1)));
TtfFont ttfFont1 = Aspose.Font.Font.Open(fd1) as TtfFont;
            
string fileName2 = dataDir + "Lora-Bold.ttf"; //Font file name with full path
FontDefinition fd2 = new FontDefinition(FontType.TTF, new FontFileDefinition("ttf", new FileSystemStreamSource(fileName2)));
TtfFont ttfFont2 = Aspose.Font.Font.Open(fd2) as TtfFont;

DrawText("Hello world", ttfFont1, 14, Brushes.White, Brushes.Black, dataDir + "hello1_montserrat_out.jpg");
DrawText("Hello world", ttfFont2, 14, Brushes.Yellow, Brushes.Red, dataDir + "hello2_lora_out.jpg");

使用C＃渲染Type1字体的文本

下面的代码示例演示如何使用C＃以Type1字体呈现文本。

string fileName = dataDir + "courier.pfb"; //Font file name with full path

FontDefinition fd = new FontDefinition(FontType.Type1, new FontFileDefinition("pfb", new FileSystemStreamSource(fileName)));
Type1Font font = Aspose.Font.Font.Open(fd) as Type1Font;
            

DrawText("Hello world", font, 14, Brushes.White, Brushes.Black, dataDir + "hello1_type1_out.jpg");
DrawText("Hello world", font, 14, Brushes.Yellow, Brushes.Red, dataDir + "hello2_type1_out.jpg");